It has been suggested in the literature, but never conclusively documented, that frozen-deglycerolized red cells (FDRC) could prevent post-transfusion hepatitis (PTH). In a recent experiment, we showed in a chimpanzee model that FDRC did not prevent the development of type B PTH. Since 80-90% of PTH is now due to the non-A/non-B agent or agents, it seems appropriate to determine if FDRC play any role in prevention of this disease. Such a study now becomes feasible because of the recent transmissions of non-A/non-B hepatitis in chimpanzees. In this study, we will utilize whole blood from a donor shown to transmit non-A, non-B hepatitis to both humans and chimpanzees. The blood will be frozen and deglycerolized by standard techniques and then tested for infectivity in chimpanzees.